The invention relates to a low-pressure mercury vapor discharge lamp provided with a discharge vessel which encloses a discharge space provided with a filling of mercury and a rare gas in a gastight manner, the low-pressure mercury vapor discharge lamp comprises discharge means for generating and maintaining a discharge in the discharge space, the discharge vessel being translucent to radiation generated in the discharge space and said discharge vessel having a first and a second end portion.
A low-pressure mercury vapor discharge lamp of the kind mentioned in the opening paragraph is known from U.S. Pat. No. 4,544,997. The inner surface of the tubular wall of the discharge vessel of the known lamp is provided with a translucent layer of a metal oxide. The metal oxide layer serves to counteract that the wall of the discharge vessel is attacked owing to interactions with mercury and thus has a favorable influence on the maintenance of the radiation output of the lamp.
The mercury consumption of the lamp, i.e. the quantity of mercury bound to lamp components during lamp operation and thus no longer available for the operation of the lamp, is comparatively low owing to the metal oxide layer as compared with that in lamps which lack such a metal oxide layer. Nevertheless, a comparatively large mercury dose is necessary also for the known lamp if a sufficiently long lamp life is to be realized. This forms an environmental hazard in the case of inexpert waste disposal after the end of lamp life.